Quaternary ammonium epoxy resin dispersion with boric acid for cationic electro-deposition

ABSTRACT

Synthetic resins which are water-dispersible epoxy resins having epoxy groups, chemically-bound quaternary ammonium base salts, can be dissolved or dispersed in water to provide aqueous coating compositions. Such compositions, in which these resins are the major resinous component, can be applied by electrodeposition and deposit on the cathode to provide coatings of improved properties, including a high degree of resistance to corrosion or staining.

United States Patent 1191 Bosso et al. Oct. 1, 1974 [54] QUATERNARYAMMONIUM EPOXY RESIN 2,909.448 10/1959 Schroeder 260/29.2 EP

DISPERSION WITH BORIC ACID FOR ee CATIONIC ELECTRO-DEPOSITION 3,134,7545/1964 Brunner et al 260/47 EC [75] Inventors: Joseph F. Bosso; LomerBurrell; 3,257,347 6/1966 Woods et a1. 260/29.2 15? Marco wismer, all ofGibsonia Pa 3,30l,804 H1967 Zora Ct a1. 260/29.2 EP 3,336,253 8/1967Wong et al 260/29.2 EP [73] Ass1gnee: PPG Industries, Inc., PittsburgPa. 3,395,107 7/1968 Burnthall et a1. 260/29.2 51 3,449,281 6/1969Sullivan et a1. 260/29.2 EP [22] 1972 3,619,398 11 1971 Bosso et a1260/29.2 EP [21] APPL 7 3,632,559 1/1972 Matter et a1. 260/29.2 EP3,702,351 11/1972 Tesson ct al.... 260/29.2 EP Related US ApplicationData 3,715,335 2/1973 Bagskai 260/29.2 EP [60] Division of Ser. No.167,470, July 29, 1971, which is a continuation-in-part of Ser. Nos.840,847, July 10, 1969, abandoned, and Ser. No. 840,848, July 10,Prl'flary Y 1969, abandoned, and Ser. No. 100,825, Dec. 22, 148mm"!Koecke" 1970, abandoned, and Ser. No. 100,834, Dec. 22, Attorney, g or.Carl rml 1970, abandoned, said Ser. No. 100,825, and Ser. No. 100,834,each is a continuation-in-part of Ser. No. 56,730, July 20, 1970,abandoned, which is a continuation-in-part of Ser. No. 772,366, Oct. 31,[57] ABSTRACT 1968 abandoned Synthetic resins which arewater-dispersible epoxy resins having epoxy groups, chemically-boundquaternary [52] Cl 260/29'2 5 34 ammonium base salts, can be dissolvedor dispersed in water to provide aqueous coating compositions. Such 2; S13/ g gg gg g 3 compositions, in which these resins are the major res- 1o arch B 26O29 2 inous component, can be applied by electrodepositionand deposit on the cathode to provide coatings of improved properties,including a high degree of resis- [56] References cued tance tocorrosion or staining.

UNITED STATES PATENTS 2,676,166 4/1954 Webers 260/2 EP 24 Claims, N0Drawings QUATERNARY AMMONIIJM EPOXY RESIN DISPERSION WITH BORIC ACID FORCATIONIC ELECTRO-DEPOSITION CROSS-REFERENCES TO RELATED APPLICATIONSThis application is a division of copending US. Application Ser. No.167,470, filed July 29, 1971, which in turn is a continuation-in-part ofcopending US. Applications Ser. Nos. 840,847 and 840,848, filed July 10,1969 now abandoned, and also a continuation-in-part of copending US.Applications Ser. Nos. 100,825 and 100,834, filed Dec. 22, 1970 nowabandoned, both of which, in turn, are continuations-in-part ofcopending U.S. Applications Ser. No. 56,730, filed July 20, 1970 nowabandoned, which is a continuation-in-part of copending US. ApplicationSer. No. 772,366, filed Oct. 31, 1968 now abandoned.

BACKGROUND OF THE INVENTION Electrodeposition, although known for sometime, hasonly recently become of commercial importance as a coatingapplication method. Along with the increased use of such methods hasbeen the development of certain compositions which can providesatisfactory coatings when applied in this manner. While manycompositions can be electrodeposited, most coating compositions whenapplied using electrodeposition techniques do not produce commerciallyusable coatings. Moreover, electrodeposition of many coating materials,even when otherwise successful, is attended by various disadvantagessuch as non-uniform coatings and by poor throwing power. In addition,the coatings obtained are in most instances deficient in certainproperties essential for their utilization in many applications forwhich electrodeposition is otherwise suited. In particular, propertiessuch as corrosion resistance and alkali resistance are difficult toachieve with the resins conventionally employed in electrodepositionprocesses. This is especially true with the conventionalelectrodeposition vehicles, which contain polycarboxylic acid resinssolubilized with a base; these deposit on the anode and because of theiracidic nature tend to be sensitive to common types of corrosive attack,e.g., by salt, alkali, etc. Many electrodeposited anodic coatings aresubject to discoloration or staining because of dissolution of metalions at the anode.

Epoxy resins are among the most useful resins for many purposes and haveexcellent corrosion resistance and other properties. They are employedin many coatings, but have not been employed in water-dispersiblecompositions suitable for application by electrodeposition because theycannot be adequately dispersed in water under the conditions required insuch processes. Esterified epoxies have been utilized, but these actsimilarly to the polycarboxylic acid resins, and while offering manyadvantages over such polycarboxylic acid resins, are still subject tomany of their disadvantages.

ln copending Application Ser. No. 772,353, filed on Oct. 31, 1968 nowU.S. Pat. No. 3,619,398, there aredescribed certain water-dispersedepoxy compositions which can be electrodeposited with good results.These compositions are typically stable emulsions and although they arevery useful and provide highly desirable coatings they are still subjectto certain disadvantages, such as low throwing power and difficulty incontrolling film thickness, attributed to the hydrophobic nature of theepoxy reaction products therein.

In copending application Ser. No. 100,834, filed Dec. 22, 1970, nowabandoned there are disclosed cathodic electrodepositable epoxy resinscontaining epoxy groups, quaternary ammonium salts, boron andoxyalkylene groups and aqueous dispersions thereof.

SUMMARY OF THE INVENTION It has now been found that synthetic resinswhich are ungelled water-dispersible epoxy resins having epoxy groupsand chemically-bound quaternary ammonium base groups can be easilyutilized to provide clear or colloidal water solutions.Chemically-bound, as utilized herein, includes salts as well as covalentbonding. These compositions, when solubilized with an acid having adissociation constant greater than about 1 X 10 can be applied byelectrodeposition to provide adherent coatings having excellentproperties. When electrodeposited, they deposit on the cathode. Whenemployed in aqueous compositions for electrodeposition, the above resinsform the major resinous constituent of the composition, either as thesole resinous component or along with one or more other resinous orfilmforming materials. Among the properties of the coatings herein arethe desirable properties ordinarily associated with electrodepositableresins known heretofore and, in addition, these reaction productsprovide coatings of unique advantages and properties. These include ahigh level of resistance to salt spray, alkali and similarly corrosiveelements, even over unprimed metals and in the absence ofcorrosive-inhibiting pigments, and are resistant to staining anddiscoloration which is often encountered with electrodeposited coatingsbased on anodic-type resins. These resins, when solubilized with an acidhaving a dissociation constant greater than 1 X 10 have appreciablyhigher throw power and better film-forming characteristics than insimilar compositions, for example, those described in US. Pat. No.3,301,804.

DETAILED DESCRIPTION OF THE INVENTION The resins of the invention areungelled, waterdispersible epoxy resins having in their molecule atleast one 1,2-epoxy group per average molecule and containingchemically-bound quaternary ammonium base salts, the quaternary ammoniumbase salts being salts of boric acid and/or an acid having adissociation constant greater than boric acid, including organic andinorganic acids. Upon solubilization, at least a portion of the saltmust be a salt of an acid having a dissociation constant greater thanabout l X 10 Preferably the acid is an organic, carboxylic acid. Thepresently preferred acid is lactic acid.v Preferably the resin containsfrom about 0.05 to about 16 percent by weight nitrogen and at leastabout 1 percent of said nitrogen and preferably about 20 percent, morepreferably about 50 percent, and most preferably, substantially all, ofthe nitrogen being in the form of chemically-bound quaternary ammoniumbase salt groups; preferably the remainder of said nitrogen being in theform of amino nitrogen.

The epoxy compound can be any monomeric or polytaining more than oneepoxy group per molecule. The polyepoxide can be any of the well-knownepoxides, provided it contains sufficient epoxy groups so that someresidual epoxy groups remain in the product after the oxyalkylation forreaction with the amine compound described hereinafter. Examples ofthese polyepoxides have, for example, been described in U.S. Pat. Nos.2,467,171; 2,615,007; 2,716,123; 3,030,336; 3,053,855 and 3,075,999. Auseful class of polyepoxides are the polyglycidyl ethers of polyphenols,such as Bisphenol A. These may be produced, for example, byetherification of a polyphenol with epichlorohydrin or dichlorohydrin inthe presence of an alkali. The phenolic compound may bebis(4-hydroxyphenyl)-2,2- propane, 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)1,l-ethane, bis(4-hydroxyphenyl) 1 ,1- isobutane; bis(4-hydroxytertiary-butylphenyl )2 ,2- propane,bis(2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, or the like.Another quite useful class of polyepoxides are produced similarly fromnovolak resins or similar polyphenol resins.

Also suitable are the similar polyglycidyl ethers of polyhydric alcoholswhich may be derived from such polyhydric alcohols as ethylene glycol,diethylene glycol, triethylene glycol, 1,2-propylene glycol, l,4-butylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol,bis(4-hydroxycyclohexyl)-2,2-propane, and the like.

There can also be used polyglycidyl esters of polycarboxylic acids whichare produced by the reaction of epichlorohydrin or a similar epoxycompound with an aliphatic or aromatic polycarboxylic acid, such asoxalic acid, succinic acid, glutaric acid, terephthalic acid,2,6-naphthylene dicarboxylic acid, dimerized linolenic acid, and thelike. Examples are diglycidyl adipate and diglycidyl phthalate.

Also useful are polyepoxides derived from the epoxidation of anolefinically unsaturated alicyclic compound. Included are diepoxidescomprising in part one or more monoepoxides. These polyepoxides arenonphenolic and are obtained by epoxidation of alicyclic olefms, forexample, by oxygen and selected metal catalysts, by perbenzoic acid, byacetaldehyde monoperacetate, or by peracetic acid. Among suchpolyepoxides are the epoxyalicyclic ethers and esters, which are wellknown in the art.

Another class of polyepoxides are those containing oxyalkylene groups inthe epoxy molecule. such oxyalkylene groups are typically groups of thegeneral formula:

L Bi.

where R is hydrogen or alkyl, preferably lower alkyl (e.g., having 1 to6 carbon atoms) and where, in most instances, m is l to 4 and n is 2 to50. Such groups can be pendent to the main molecular chain of thepolyepoxide or part of the main chain itself. The proportion of theoxyalkylene groups in the polyepoxide depends upon many factors.including the chain length of the oxyalkylene group, the nature of theepoxy and the degree of water solubility desired. Usually the epoxycontains at least about 1 percent by weight or more, and

preferably percent or more, of oxyalkylene groups.

Some polyepoxides containing oxyalkylene groups are produced by reactingsome of the epoxy groups of a polyepoxide, such as the epoxy resinsmentioned above, with a monohydric alcohol containing oxyalkylenegroups. Such monohydric alcohols are conveniently produced byoxyalkylating an alcohol, such as methanol, ethanol, or other alkanol,with alkylene oxide. Ethylene oxide, 1,2-propylene oxide and 1,2-butylene oxide are especially useful alkylene oxides. Other monohydricalcohols can be, for example, the commercially available materials knownas Cellosolves and Carbitols, which are monoalkyl ethers of polyalkyleneglycols. The reaction of the monohydric alcohol and the polyepoxide isgenerally carried out in the pres ence of a catalyst; formic acid,dimethylethanolamine, diethylethanolamine, N,N-dimethylbenzylamine and,in some cases, stannous chloride are useful for this purpose.

Similar polyepoxides containing oxyalkylene groups can be produced byoxyalkylating the epoxy resin by other means, such as by direct reactionwith an alkylene oxide.

The polyepoxide employed to produce the foregoing epoxies containingoxyalkylene groups should contain a sufficient number of epoxy groups sothat the average number of residual epoxy groups per moleucle remainingin the product after the, oxyalkylation is greater than 1.0. Whereoxyalkylene groups are present, the epoxy resin preferably contains fromabout 1.0 to about 90 percent or more by weight of oxyalkylene groups.

Other epoxy-containing compounds and resins include nitrogeneousdiepoxides such as disclosed in U.S. Pat. No. 3,365,471; epoxy resinsfrom 1,1-methylene bis(S-substituted hydantoin), U.S. Pat. No.3,391,097; bis-imide containing diepoxides, U.S. Pat. No. 3,450,711,epoxylated aminomethyl diphenyl oxides, U.S. Pat. No. 3,312,664;heterocyclic N,N'-diglycidyl compounds, US. Pat. No. 3,503,979; aminoepoxy phosphonates, British Pat. 1,172,916; 1,3,5-triglycidylisocyanurates, as well as other epoxy-containing materials known in theart. I

The resins of the invention are formed by reacting the epoxy compoundwith an amine salt to form quaternary amine base group-containingresins.

Examples of salts which may be employed include salts of ammonia,primary, secondary or tertiary amines, and preferably tertiary amines;salts of boric acid or an acid having a dissociation constant greaterthan that of boric acid and preferably an organic acid having adissociation constant greater than about 1 X 10". The presentlypreferred acid is lactic acid. Such acids include, lactic acid, aceticacid, propionic acid, butyric acid, hydrochloric acid, phosphoric acid,sulfuric acid. The amines may be unsubstituted amines or aminessubstituted with non-reactive constituents such as halogens orhydroxylamines. Specific amines include dimethylethanolamine salts ofboric, lactic, propionic, butyric, hydrochloric, phosphoric and sulfuricor similar salts of triethylamine, diethylethanolamine, trimethylamine,diethylamine, dipropylamine, l-amino-Z- propanol, and the like. Alsoincludes are ammonium borate, ammonium lactate, ammonium acetate,ammonium chloride, ammonium phosphate. as well as other amine andammonium salts as defined above.

A distinct class of amine compounds within the broader class is aminecontaining one or more secondai y or tertiary amino groups and at leastone hydroxyl where R and R are, preferably, methyl, ethyl, or loweralkyl groups, butcan be essentially any other organic radical, so longas they do not interfere with the desired reaction. Benzyl, alkoxyalkyl,and the like are examples. R can also be hydrogen. The nature of theparticular groups is less important than the presence of a secondary ortertiary amino nitrogen atom, and thus higher alkyl, a'ryl, alkaryl,aralkyl, and substituted groups of the types can be present. The grouprepresented by R is a divalent organic group, such as alkylene orsubstituted-alkylene, e.g., oxyalkylene or poly- (oxyalkylene), or, lessdesirably, arylene, alkarylene or -substituted-arylene. R can also be anunsaturated group, e.g., an alkylene group such as CH==CH or R CH=-.

Other groups represented by R include cyclic or aromatic groups; onetype of useful amine, for instance, is represented by the formula:

OH I

1 CHaN where n is l to 3. Dialkanolamines, of the general formula R,N(ROH) and trialkanolamines, of the general formula N(R OH are also useful.

Some examples of specific amines are as follows:

diinethylethanolamine dimethylpropanolamine dimethylisopropanolaminedimethylbutanolamine diethylethanolamine ethylethanolamine'methylethanolamine N-benzylethanolamine diethanolamine triethanolaminedimethylaminomethyl phenol tris(dimethylaminomethyl)phenol2-[Z-(dimethylamino)ethoxy]ethanol l-1-(dimethylamino)-2-propoxy]-2-propanol 2-(2-[2(dimethylamino)ethoxy]ethoxy )ethanoll-[2-(dimethylamino)ethoxy]-2-propanol l-(l-ldimethylamino)-2-propoxy]-2-propoxy)-2- propanol Another distinctclass of amine compound within the broader class is any amine containingone or more secondary or tertiary amino groups and at least one terminalcarboxyl group. In most cases where a carboxyl amine is employed, itcorresponds to the general formula:

NRaCOOH where R andR are each preferably methyl, ethyl, or other loweralkyl groups, but can be essentially any other organic radical, so longas they do not interfere with the desired reaction. Benzyl, alkoxyalkyl,and the of the particular groups is less important than the presence ofa secondary or tertiary amino nitrogen atom, and thus higher alkyl,aryl, alkaryl, aralkyl, and substituted groups of these types can bepresent. The group represented by R is a divalent organic group, such asalkylene or substituted alkylcne. e.g.. oxynlkylcne orpoly(oxyalkylene), or, less desirably, arylene, alkarylene orsubstituted arylene. R can also be an unsaturated group, e.g., .analkenylene group.

Such amines can be prepared by known methods. For example, an acidanhydride, such as succinic anhydride, phthalic anhydride or maleicanhydride, can be reacted with an alkanolamine, such asdimethylethanolamine or methyldiethanolamine; the group represented by Rin the amines produced in such cases contain ester groups. Other typesof amines are provided, for example, by reacting an alkylamine with analkyl acrylate or methacrylates such as methyl or ethyl acrylate ormethacrylate as described in US. Pat. No. 3,419,525. Preferably theester group is subsequently hydrolyzed to form a free carboxyl group.Other methods for producing amines of different types can also beemployed.

It can beseen that the groups represented by R, can be of widely varyingtypes; some examples are:

R'OCOR -(RO),,COR where each R is alkylene, such as CH CH T EP TL 1,l-dimethyl-2-( Z-di'methylaminoethoxy )ethyl hydrogen succinate 2- l2-( Z-dimethylaminoethoxy )ethoxy ethyl hydrogen maleatebeta-(dimethylamino)propionic acid beta-(dimethylamino)isobutyric acidbeta-(diethylamino)propionic acid l-methyl-2-(dimethylamin0)ethylhydrogen maleate 2-(methylamino)ethyl hydrogen succinate3-(ethylamino)propyl hydrogen maleate 2l2-(dimethylamino)ethoxylethylhydrogen adipate N,N-dimethylaminoethyl hydrogen azelate 7di-(N,N-dimethylaminoethyl)hydrogen late N,N-dimethylaminoethyl hydrogenitaconate 1-( l-[ 1(dimethylamino)-2-propoxy]-2-propoxy)-2- propylhydrogen maleate 2-[2-(Z-(dimethylamino)ethoxy]ethoxy)ethoxy]ethylhydrogen succinate ln one embodiment, the epoxy compounds describedabove may be reacted with an ester of boric acid or a compound which canbe cleaved to form boric acid in a medium containing water andpreferably an amino containing boron ester and/or a tertiary amine saltof boric acid to produce the epoxy reaction products of the invention.The boron compound component utilized in producing the reaction productscan be, for example, any triorganoborate in which at least one of theorganic groups is substituted with an amino group. Structurally, suchesters are esters of boric acid or a dehydrated boric acid such asmetaboric acid and tetraboric acid, although not necessarily producedfrom such acids. In most cases the boron esters employed correspond toone of the general formulas:

tricarbally- /OR RO-B where the R groups are the same or differentorganic groups. The groups represented by R above can be virtually anyorganic group, such as hydrocarbon or substituted hydrocarbon, usuallyhaving not more than 20 carbon atoms and preferably not more than about8 carbon atoms. The preferred esters have alkyl groups or polyoxyalkylgroups. At least one of theorganic groups contains an amine group, i.e.,a group of the structure:

where R, and R are hydrogen or preferably, methyl, ethyl or other loweralkyl groups, but can be essentially any other organic radical, so longas they do not interfere with the desired reaction. The nature of theparticular groups isless important than the presence of an aminonitrogen atom, and thus higher alkyl, aryl, alkaryl, aralkyl andsubstituted groups of these types can be present. While both R and R canbe hydrogen (i.e., the amino group is a primary amino group), it is preferred that at least one be an alkyl or other organic group, so that theamino group is a secondary or tertiary.

The preferred boron esters correspond to the formula: A.

/Ri X-O-R -N where X has the'structure:

rat-o R4\ /B- or /B- R and R being divalent organic radicals, such asalkylene or substituted-alkylene, e.g., oxyalkylene or poly-(oxyalkylene), or, less desirably, arylene, alkarylene or substitutedarylene. R and R, can be alkyl, substituted alkyl, aryl, alkaryl, orother residue from essentially any monohydroxy alcohol derived byremoval of the hydroxyl group. R and R can be the same or different.

Examples of boron esters within the above class include:

2-(beta-dimethylaminoisopropoxy )-4,5-dimethyll ,3,2-dioxaborolane 2-(beta-diethylaminoethoxy )-4,4,6-trimethyll ,3 ,2-

dioxaborinane 2-(beta-dimethylaminoethoxy)-4,4,6-trimethyl- 1,3,2-dioxaborinane 2-( beta-diisopropylaminoethoxy )-l ,3 ,2-

dioxaborolane 2-( beta-dibutylaminoethoxy )-4-methyll ,3 ,2

dioxaborinane 2-( beta-diet'hylaminoethoxy l ,3 ,2-dioxaborinaneZ-(gamma-aminopropoxy)-4-methyl-1,3 ,2-

dioxaborinane 2-( beta-methylaminoethoxy )-4,4,6-trimethyl-l ,3 ,2-

dioxaborinane Z-(beta-ethylaminoethoxy )-l ,3 ,6-trioxa-2-boracyclooctane 2-( gamma-dimethylaminopropoxy )-l ,3,6,9-tetraoxa-2-boracycloundecane 2-( beta-dimethylaminoethoxy )-4-(4-hydroxybutyl l,3,2-dioxaborolane Reaction product of (CH ),NCH CH OH lactic acid B 0neopentyl glycol A number of such boron esters are known; many aredescribed, for example, in U.S. Pat. Nos. 3,301 ,804 and 3,257,442. Theycan be prepared by reacting one mole of boric acid (or equivalent boricoxide) with at least 3 moles of alcohol, at least one mole of thealcohol being an amino-substituted alcohol. The reaction is ordinarilycarried out by refluxing the reactants with removal of the water formed.

The amine salts and the epoxy compound are reacted by mixing thecomponents, usually at moderately elevated temperatures such as 1 10C.Alternatively in a less preferred embodiment in the case of a tertiaryamine, the amine may be added to the epoxy compound and the acidutilized to form the appropriate salt may be subsequently added, even aslate as the solubilization step. A solvent is not necessary, althoughone is often used in order to afford better control of the reaction.Aromatic hydrocarbons or monoalkyl ethers of ethylene glycol aresuitable solvents. The proportions of the amine salt and the epoxycompound can be varied and the optimum proportions depend upon theparticular reactants. Ordinarily, however, from about one part to about50 parts by weight of the salt per parts of epoxy compound is employed.The proportions are usually chosen with reference to the amount ofnitrogen, which is typically from about 0.05 to about 16 percent basedon the total weight of the amine salt and the epoxy compound. Since theamine, salt reacts with the epoxide groups of the epoxy resin employed,in order to provide an epoxy group-containing resin, the

stociometric amount of amine employed should be less than thestociometric equivalent of the epoxide groups present, so that the finalresin is provided with one epoxy group per average molecule.

The particular reactants, proportions and reaction conditions should bechosen in accordance with considerations well-known in the art, so as toavoid gellation of the product during the reaction. For example,excessively severe reaction conditions should not be employed.Similarly, compounds having reactive substituents should not be utilizedalong with epoxy compounds with which those substituents might reactadversely at the desired conditions.

The product forming the resin of the invention may be crosslinked tosome extent; however, it remains soluble in certain organic solvents andcan be further cured to a hard, thermoset state. It is significantlycharacterized by its epoxy content and chemically-bound quaternaryammonium content.

Aqueouscompositions containing the above reaction products are highlyuseful as coating compositions and can be applied by any conventionalmethod, such as by dipping, brushing, etc. They are, however, eminentlysuited to application by electrodeposition.

Where the resin of the invention was prepared employing at least in parta salt of an acid having a dissociation constant greater than l X 10",it is not necessary to add a solubilizing agent to the product to obtaina suitable aqueous electrodepositable composition, although an acid oracidic solubilizing agent can be added if desired. Where boric acidsalts or similar boron compounds as described above are employed toprepare the resin without the presence of a salt of an acid having adissociation constant greater than 1 X 10 compositions within the scopeof this invention can be prepared by adding such an acid, the strongeracid replacing the boron compound in the resin and the boron compoundforming substantially undissociated boric acid remaining in the aqueousmedia and being at least partially codeposited with the resin.

The presence of a boron compound in the eEctrodeposited film is ofsubstantial benefit in that boron compounds apparently catalyze the cureof the deposited film, allowing lower cure temperatures and/or harderfilms.

The acid or acidic solubilizing agent niaybe any acid having adissociation constant greater than 1 X 10". Preferably, the acid oracidic solubilizing agent should be an organic acid having adissociation constant greater than about 1 X 10 the presently preferredacid being lactic acid. The addition of acid aids in stabilizing theresin, since the epoxy may tend to further polymerize on storage underhighly alkaline conditions; in some cases, the acid also helps to obtainmore complete dissolution of the resin. It is also desirable toelectrodeposit these coatings from an acidic or only slightly basicsolution (e.g., having a pH between about 3 and about 8.5 and theaddition of acid thus is often useful to achieve the desired pH. 4

' wfierea'aa'rpaxyiamrfi is ei'ripifidin'i'ofniifig the" resin of theinvention, the resultant resin contains a Zwitterion, or internal salt,that is, an interaction between the quaternary group formed and thecarboxyl group present, the carboxyl group displaying a dissociationconstant greater than 1 X 10 The resultant resin is inherentlyself-solubilized without the use of external solubilizing agents.

solidstzed concentrate or the electrodeposition bath,

Thus, the resin in aqueous medium can be characterized as awater-containing medium containing an ungelled water-dispersible epoxyresin having at least one 1,2-epoxy group per average molecule, andchemicallybound quarternary ammonium base salts.

/or a borate or boric acid complex.

The concentration of the product in water depends upon the processparameters to be used and is, in gen- 7 eral, not critical, butordinarily the major proportion of the aqueous composition is water, e.g., the composition may contain from one to 25 percent by weight of theresin.

Preferably, the electrodepositable compositions of the invention containa coupling solvent. The use of a coupling solvent provides for improveddeposited film appearance. These solvents include hydrocarbons,alcohols, esters, ethers, and ketones. The preferred coupling solventsinclude monalcohols, glycols, and polyols as well as ketones and etheralcohols. Specific coupling solvents include isopropanol, butanol,isophorone, Pentoxane (4-methoxy-4-methyl pentanone-2), ethylene andpropylene glycol, the momomethyl, monoethyl and monobutyl ethers ofethylene glycol, 2-ethylhexanol, and hexyl Cellosolve. The presentlypreferred coupling solvent is Z-ethylhexanol. The amount of solvent isnot unduly critical, generally between about 0.1 percent and about 40percent by weight of the dispersant may be employed, preferably betweenabout 0.5 to about 25 percent by weight of the dispersant is employed.

While the resins liereinabove described may be electrodeposited assubstantially the sole resinous component of the electrodepositedcomposition, it is frequently desirable in order to improve or modifyfilm appearance and/or film properties, to incorporate into theelectrodepositable compositions various nonreactive and reactivecompounds or resinous materials such as plasticizing material includingN-cyclohexyl-ptoluene sulfonamide, orthoand para-toluene sulfonamide,N-ethyl-orthoand para-toluene sulfonamide, aromatic and aliphaticpolyether polyols, phenol resins including allyl ether containingphenolic resins, liquid epoxy resins, quadrols, polycaprolactones;triazine resins such as melamine-based resins and benzoguanamine-basedresins, especially alkylated formaldehyde reaction products thereof;urea formaldehyde resins, acrylic resins, hydroxy and/or carboxylgroupcontaining polyesters and hydrocarbon resins.

Other materials include esters such as butylbenzyl phthalate, diocty]phthalate, methyl phthalylethyl glycolate, butylphthalylbutyl glycolate,cresyl diphenyl phosphate, Z-ethylhexyl diphenyl phosphate, polyethyleneglycol 200 dibenzoates as well as polyesters, 2,2,4- trimethylpentanediol monoisobutyrate (Texanol).

In most instances, a pigment composition and, if desired, variousadditives such as anti-oxidants, surfactants, or wetting agents, forexample, Foam Kill 639 (a hydrocarbon oil-containing inert diatomaceousearth), as well as glycolated acetylenes (the Surfynols, for example),sulfonates, sulfated fatty amides, and alkylphenoxypolyoxyalkylenealkanols, and the like, are included. The pigment composition may be ofany conventional type, comprising, for example, iron oxides, leadoxides, strontium chromate, carbon black, titanium dioxide, talc, bariumsulfate, as well as color pigments such as cadmium yellow, cadmium red,chormic yellow, and the like.

In the electrodeposition processes employing the aqueous coatingcompositions described above, the aqueous composition is placed incontact with an electrically-conductive anode and anelectricallyconductive cathode, with the surface to be coated being thecathode, while in contact with the bath containing the coatingcomposition, an adherent film of the coating composition is deposited onthe cathode. This is directly contrary to the processes utilizingpolycarboxylic acid resins, as in the prior art, and the advantagesdescribed are, in large part, attributed to this cathodic deposition.

The conditions under which the electrodeposition is carried out are, ingeneral, similar to those used in electrodeposition of other types ofcoatings. The applied voltage may be varied greatly and can be, forexample, as low as one volt or as high as several thousand volts,although typically between 50 and 500 volts. The current density isusually between about 1.0 ampere and I amperes per square foot, andtends to decrease during electrodeposition.

The resin of the invention when freshly electrodeposited on the cathodecontains quaternary ammonium base groups. The acid moiety which formsthe salt migrates at least in part toward the anode. Where theelectrodeposition bath contains boron, the electtrodeposited resinfurther contains boron which is bonded with the basic groups present inthe film which has electrodeposited upon the cathode. The amounts ofbonded boron in the electrodeposited film increase with increasing boronconcentration in the bath to a saturation value, dependent on the numberof basic groups in the concentration and the basicity of the basegroups.

The film, while it may be crosslinked to some extent, remains soluble incertain organic solvents.

The freshly-deposited, uncured electrodeposited film may becharacterized as follows: an epoxy resin electrodeposited upon anelectrically-conductive substrate comprising an ungelled epoxy resinhaving at least one l,2-epoxy group per average molecule,chemicallybound quaternary ammonium base, and where boron is present inthe electrodepositable composition, 0.01 to about 8 percent by weight ofboron in the form of quaternary and amine borates and boron complexes.

The method of the invention is applicable to the coating of anyconductive substrate, and especially metals such as steel, aluminum,copper, magnesium, or the like. After deposition, the coating is cured,usually by baking at elevated temperatures. Temperatures of 250F. to500F. for one to 30 minutes are typical baking schedules utilized.

During the cure, especially at elevated temperatures, at least asubstantial portion of the quaternary ammonium base decomposes totertiary amine nitrogen, which aids in the crosslinking of the coating,which upon curing is infusible and insoluble. The presence of boronsalts and complexes in the film increases the rate of crosslinking,reduced the temperatures necessary for acceptable curing incommercially-reasonable times and produces coatings with improvedhardness and corrosion resistance.

As set forth above, the significant resin constituents are (A) a resinhaving epoxy groups; (B) quaternary ammonium groups; (C) salts of acidshaving a dissociation constant greater than 1 X 10 and, optionally, (D)amine groups and (E) boron. All these components may be qualitativelyand quantitatively determined by numerous methods known in the art.

Epoxy groups may be determined by the well-known pyridiniumhydrochloride method as described, for example, in .Siggia, QUANTITATIVEORGANIC ANALYSIS VIA FUNCTIONAL GROUPS, John Wiley & Sons, Inc., NewYork (1963), page 242.

The total base groups present in the polymer, that is, quaternary andamine groups present, may be determined on a separate resin sample.Usually the resin sample will be neutral. If, however, the resin isbasic, the sample should be neutralized with a known amount of the acidpresent in the resin as a salt. Where the acid present in the resin as asalt is a weak acid as compared to I-ICI, the resin is titrated withI-ICl and back-titrated with sodium hydroxide on an automatic titrator.The HCl titration yields the total base groups present. The sodiumhydroxide back-titration distinguishes quaternary groups from aminegroups. For example, a typical analysis is conducted as follows: a 10milliliter sample of an about 10 percent solids electrodeposition bathis pipetted in 60 milliliters of tetrahydrofuran. The sample is titratedwith 0.1000 normal I-ICl to the pH end point. The amount of standardacid used is equivalent to the quaternary base and amine equivalentspresent. The sample is then back titrated with 0.1000 normal sodiumhydroxide to give a titration curve with multiple end points. In atypical instance, the first end point corresponds to excess HCl. Fromthe I-ICl titration, the second end point corresponds to theneutralization of the weak acid (for example, lactic acid) and aminehydrochloride. The difference in volume between the two endpoints givesthe volume of standard base equivalent to the weak acid and aminecontent of the sample.

Whereas solvent such as propylene glycol is employed with, for example,tetrahydrofuran to maintain sample homo-geniety, boron present will alsotitrate since the borons in the form present forms an acid complex withthe propylene glcyol. Under the conditions specified, the boric acid maybe distinguished from the weak acid (e.g., lactic) by an additionalinflection point in the pH titration curve. Depending on the strength ofthe amine group present, it may be included either in the weak acid(e.g., lactic) or boric acid portion of the titration curve.

Excess weak acid or amine salt in the electrodeposition bath may bedetermined by alcoholic-KOH titration. For example, a milliliter sampleof about 10 percent solids electrodeposition bath is pipetted into 60milliliters of tetrahydrofuran and potentiometrically titrated with0.1000 normal alcoholic KOH to the first end point. The amount of KOHconsumed is equivalent to any acid or amine salt in the sample. In thecase of neutral compositions, KOH titration is a measure of the amountof amine present in the form of amine salt since the quaternary, being astrong base, will not titrate.

In the case of the presence of acid salts of strong acids, other methodsmust be employed to determine acid, amine and quaternary groups present.For example, where the resin contains amine hydrochloride and quaternaryhydrochloride groups, the resin may be dispersed, for example, in amixture of glacial acetic acid and tetrahydrofuran, the chloridecomplexed with mercuric acetate and the sample titrated with perchloricacid to yield the total amine and quaternary groups. Separate alcholicKOH titration will yield the amine groups present since the quaternaryis of comparable strength to the alcoholic KOH.

Boron may be determined as described by R. S. Braman, BoronDetermination, ENCYCLOPEDIA OF INDUSTRIAL CHEMICAL ANALYSIS, F. D. Snelland Hilton, Editors, John Wiley & Sons, Inc., New York (1968), volume 7,pages 384-423. The boron may be determined on a separate sample. Forexample, by pipetting a 10 milliliter sample of an approximately 10percent solid cationic electrodeposition bath into 60 milliliters ofdistilled water. Sufficient HCl is then added to lower the pH to about4.0. The sample is then back-titrated with 0.1000 normal sodiumhydroxide, using a Metrohm Potentiograph E-436 automatic titrator orequivalent apparatus, to the first inflection point in the pH titrationcurve. There is then added 7 grams of mannitol. The solution becomesacid and titration is then continued to the second inflection point inthe pH titration curve. The amount of base consumed between the firstand second endpoints is a measure of the number of moles or boric acidcomplex formed in the samp The above description is exemplary of thetechnique employed to quatitatively and qualitatively identify thegroups present. In specific case, analytical techniques may be adaptedto a specific resin; however, in each case, consistent with the abovedescription, there exists methods known in the art which yieldappropriate accurate determinations of the significant chemical moietycontent.

Illustrating the invention are the following examples, which, however,are not to be construed as limiting the invention to their details. Allparts and percentages in the examples, as well as throughout thisspecification are by weight unless otherwise specified. In several ofthe examples, there are employed oxyalkylene containing polyepoxidesproduced by reacting one mole of poly(oxyalkylene)glycol with two molesof polyepoxide. Polyepoxide A as utilized below is such a reactionproduct made from polypropylene glycol (molecular weight about 425) andEpon 834", which is a Bisphenol A epichlorohydrin epoxy having anaverage molecular weight of about 450 and an epoxide equivalent of225-290. Polyepoxide B is the reaction product made from polypropyleneglycol (molecular weight about 1500) and Epon 1032, aBisphenolepichlorohydrin epoxy having an average molecular weight ofabout 900 and an epoxide equivalent of about 225.

EXAMPLE A Into a reactor equipped with thermometer, stirrer,distillation apparatus with reflux condenser, water trap and means forproviding an inert gas blanket were charged 741.6 parts ofdimethylethanolamine,714 parts lactic acid and 300 parts toluene. Thereaction mixture was heated to between and 1 10C. for 4 hours. A totalof parts of water were collected with an index of refraction of n 1.377.There was then added 245 parts of boric oxide, 728 parts neopentylglycol. The reaction mixture was heated between 115C. and 128C. forapproximately 4 hours, collecting an additional 205 parts of water ofreaction n,,'-"" 1.386. The reaction product had a percent nitrogencontent of 4.51 and has a proposed structure of:

O-GH:

EXAMPLE I A reaction vessel was charged with 200 parts of an epoxy resinmade from the reaction of epichlorohydrin and Bisphenol A, having anepoxide equivalent of 290 to 335 and a molecular weight of 580-670 (Epon836). There were added 58.5 parts of Monoalcohol A, 2.3 parts ofstannous chloride and 28 parts of the dimethyl ether of diethyleneglycol, and the mixture was heated at 150C. for 3 hours. The modifiedepoxy compound obtained contained oxyalkylene groups and had an epoxideequivalent of about 890. Two hundred parts of the modified epoxycompound wereheated to 70C. with stirring and then 13 parts of2-(betadimethylaminoethoxy)-4-methyl-1,3,2-dioxaborinane were added overa 21 minute period, during which time the temperature rose to 92C. Afterfive minutes there were added 1719 parts of deionized water, withstirring, along with sufficient formic acid to make the pH of thesolution 4.4. There was obtained a colloidal dispersion having anon-volatile solids content of 9.1 percent. The solids componentanalyzes to contain quaternary base groups and boron. This dispersionwas electrodeposited using steel electrodes and the followingconditions:

Bath temperature 70F.

pH 4.4 Deposition time seconds Voltage 225 volts Current 1.5-20 amp.

There was obtained an adherent coating on the cathode which was thenbaked at 400F. for 20 minutes. The

electrodeposited wet film analyzes to contain quaternary borate andquaternary hydroxide. The cured coating was hard, smooth and adherent.having a thickness of about one mil. It was highly resistant to acetoneand had excellent salt-spray and alkali resistance. 5

EXAMPLE I] Example I was repeated except that the cathode employed wasaluminum. Similar results were obtained; the coating deposited had goodadhesion to the aluminum and other satisfactory properties.

EXAMPLE III The epoxy resin employed in this example as a reactionproduct of epichlorohydrin and Bisphenol A havl5 ing a molecular weightof 660-760 and an epoxide equivalent of 330-380 (Epon 840). It wasreacted with the following by heating at l50-155C. for 8 hours.

pleted, the temperature was 90C. and heating was continued for 2minutes. There was added 89.5 parts of deiohized water and sufficient 50percent aqueous acetic acid to make the pH 4.6. The clear solutionobtained was electrodeposited as described above and the de posited filmbaked at 375F. for 20 minutes. The glossy coating obtained was adherent.hard and flexible. and was highly resistant to acetone.

EXAMPLE V] In this example, there was employed a boron ester producedfrom one mole of boron oxide, 2 moles of dimethylethanolamine and 4moles of n-hexanol; this product was understood to bebetadimethylaminoethyl-di-n-hexyl borate, having the structure:

CoH1a-O CH3 BO-OH2CH2N/ CoHia CHz Parts by Weight Epoxy resin 445Monalcohol B 125 Formic acid (90%) 9.5 Diethylene glycol dimethyl ether63 The product had an epoxide equivalent of 737; 200 parts thereof werereacted with 16.3 parts of 2-(betadimethylaminoethoxy)-4-methyl-1,3,2-dioxaborinane in the manner of the above examples. The product.

after addition of formic acid and water was a solution having a pH of4.9 and a solids content of 38 percent;

it provided electrodeposited coatings of excellent properties.

EXAMPLE IV Example 111 was repeated except that Monoalcohol A wasemployed and the reaction product was acidified with acetic acid to a pHof 5.6. A solution of similar properties was obtained.

EXAMPLE V In this example, there was utilized an epoxy compoundcontaining oxyalkylene groups produced from the following:

Parts by Weight Epoxy resin (as in Example I) 2500 Monoalcohol A 441Formic acid (90%) v 49 This modified epoxy compound had an epoxideequiva- 50 lent of 642. To 325 parts of the epoxy compound at 70C. therewas slowly added a solution of 37.8 parts of boron ester produced fromone mole of boron oxide (B 0 2 moles of diethylene glycol and 2 moles ofdimethylethanolamine; the ester was understood to be2-(beta-dimethylaminoethoxy)-1,3 ,6-trioxa-2- boracyclooctane, havingthe structure:

carom o CH! o s-o-o'Hiom-N I 0/ OH: CHaCfiz The boron ester wasdlssolved in a mixture of 37.8 parts of butyl Carbitol acetate and 26.4parts of isophorone. After the addition, which took 20 minutes, wascomparts of the oxyalkylene-modified epoxy compound as in Example V; thereaction product acidified with acetic acid to a pH of 4.5, producedclear solution in water.

EXAMPLE VII In this example, there was utilized a boron ester made from3 moles of 1,3-butanediol, 3 moles of 2- ethylaminoethanol and 1.5 molesof B 0 The boron ester was understood to be 2-(beta-ethylaminoethoxy)-4-methyl-l,3,2-dioxaborinane, having the structure:

Pat. No. 3839252 This boron ester (17.4 parts) was reacted in the mannerof the foregoing examples with 200 parts of epoxy compound (epoxideequivalent 665) made from an epoxy resin from the reaction ofepichlorohydrin with Bisphenol A (epoxide equivalent 225-290; Epon 834),by heating the following at 108l 17C. for 6% hours:

Parts by Weight Epoxy resin 2000 Propylene gly ol (molecular weight 425)lsophorone 1S0 Dimethylbenzylamine 2.8

EXAMPLE VIII In this example, the boron ester used was made from Thisboron ester (55.5 parts) was reacted with 117 2 moles of 1,3- bgtanedioland 2 moles of 3 amino-1- propanol per mole of B and was Understood tohave the structure:

EXAMPLE lX The boron ester utilized in this example was made from 2moles of boric acid, 2 moles of neopentyl glycol, 2 moles of glycolicacid and 3 moles of dimethylethanolamine; it was understood to have thestructure:

and at least contains some salt of the apparent struc- IUIBI CHr-O O-C 0CH3 CHrC-CH: B i N-CHzCHzOH GHQ-O O-CH: CH;

Sixty-five parts of the boron ester (60 percent solids in isopropylalcohol) were reacted with 500 parts of the epoxy compound employed inExample X11 (80 percent solids). Addition of water and formic acid gavea clear solution with a pH of 7.8; it was electrodeposited at 230 voltsto give a coating which after baking at 400F. for minutes was hard,flexible and solvent resistant.

While a particular advantage of the compositions herein is the manner inwhich they electrodeposit as described above, they also can be appliedby other more conventional methods. Furthermore, although compositionsfor electrodeposition are usually neutralized to an acidic pH, suchcompositions in many cases are not neutralized; also, certain reactionproducts which are less desirable in an electrodeposition process can beapplied in other ways to give coatings suitable for many purposes. Thefollowing examples illustrative such embodiments.

EXAMPLE X A mixture of 280 parts of epoxy resin from the reaction ofepichlorohydrin with polypropylene glycol (Dow Epoxy Resin 736 epoxideequivalent 186 and molecular weight 372) and 342 parts of Bisphenol Awere heated with 1 1 parts of 85 percent formic acid for 10 hours atll50C. The product (547 parts) was reacted with 1070 parts ofepichlorohydrin in the presence of sodium hydroxide. The product, afterstripping to remove excess epichlorohydrin, was an epoxy compoundcontaining oxyalkylene groups in the polymer chain and having an epoxideequivalent of 528.

The epoxy compound thus obtained was mixed with 42 parts of butylCellosolve acetate and reacted with 30.4 parts of2-(beta-dimethylaminoethoxy)-4-methyl- 1,3,2-dioxaborinane in the mannerdescribed above; the reaction product was acidified with aqueous aceticacid to a pH of 5.2. There was obtained a colloidal solution which waselectrodeposited as above with good results. The coating deposited onthe cathode and after baking at 350F. for 30 minutes was adherent andhad good solvent resistance, although somewhat soft.

EXAMPLE XI Into a reactor-was charged 1770 parts of Epon 829 and 302parts of Bisphenol A. The mixture was reacted at 170180C. for 45minutes. The reaction mixture was then cooled at 130C. There was thenadded 790 parts of polypropylene glycol (molecular weight 600) and thereaction mixture held at 130C. until the reaction mixture reached aGardner-Holdt viscosity of L-N, measured at percent solids in 90/ 10isophorone/toluene mixture. The approximate reaction time for this stepwas about 5 hours. The reaction mixture was then cooled to 120C. andthere was then added 6 parts of a 90 percent formic acid solution toneutralize the amine present. The reaction mixture was then cooled to C.and there was then added 318 parts of the boron compound of Example A,supra, and 82 parts of isopropanol over a 20 minute period, increasingthe temperature during that period from 70 to 90C. The

mixture was held at 95C. for 5 minutes after the addition was complete.There was then slowly added 500 parts of water. When the mixture washomogeneous there was slowly added 15.5 parts of a surfactant (Foam Kill639)'and 200 parts of 2-ethylhexanol. There was then added an additional840 parts of water.

This composition contained 0.225 milliequivalents of quaternarygroups/gram, 0.213 milliequivalents of lactic acid/gram and 0.228milliequivalents of boron/- gram.

The composition above, when electrodeposited from a 10 percent solidsaqueous electrodeposition bath (F.) at 250 volts for seconds onphosphatized steel panels, then rinsed and baked for 30 minutes at 350F.yielded a 0.6 mil film with a greater than 6 H pencil hardness which washighly acetone resistant and had excellent salt spray resistance.

EXAMPLE Xll An amine of the formula (CH NCH CH COOH was produced fromthe reaction of dimethylamine (25 percent solution-in water) with methylacrylate, as described in U.S. Pat. No. 3,419,525. This amine (50 parts)was added to a reaction vessel containing 450 parts of Polyepoxide A at65C. The temperature rose to 82C. in 20 minutes; 850 parts of deionizedwater were slowly added with stirring over a period of 45 minutes. Theproduct was a yellow, clear solution having a solids content of 37.3percent and an epoxy value of 6361.

60 seconds 400 volts 0.4 amp. max.

Bath temperature Deposition time Voltage Current There was obtained anadherent coating on the cathode which was then baked at 400F. forminutes. The cured coating was hard, flexible, and adherent, having athickness of about 1.2 mil. It was highly resistant to acetone.

EXAMPLE Xlll Example Xll was repeated except that the cathode employedwas aluminum. Similar results were obtained.

EXAMPLE XIV An amine of the formula (CH NCH CH OCOCH CH COOH wasproduced by reacting dimethylethanolamine with succinic anhydride. Thisamine (4.7 parts) was reacted with 87 parts of Polyepoxide B at 70C. anddiluted with deionized water to a solids content of 59 percent. A 3 milwet film of this resin solution was drawn on a steel panel and baked at350F. for 10 minutes. A hard glossy cured adherent coating was obtained,having excellent solvent resistance.

The resin solution was further diluted to 10 percent solids withdeionized water and formic acid added to a pH of 45. Electrodepositionof this product using steel electrodes at 250 volts for 90 secondsprovided an adherent coating on the cathode. After baking at 350F. for10 minutes, the coating had good solvent resistance.

EXAMPLE XV A reaction vessel containing 53.5 parts of Polyepoxide A (80percent solids in isophorone) was heated to 70C. There were added 3parts of an amine produced by reacting dimethylethanolamine withdodecylsuccinic anhydride, and then there were added 6 parts of a secondamine produced from dimethylethanolamine and maleic anhydride. Duringthe second addition the temperature was raised to 95C. and stirring wascontinued for minutes at this temperature. The product when diluted withwater and electrodeposited, as in the above examples, provided anadherent solvent-resistant coating.

EXAMPLE XVI and the composition electrodeposited, using an aluminumcathode, at 150 volts for 15 seconds; the maximum current was 2.9 amps.An adherent coating was obtained on the cathode which after baking at400F. for 30 minutes was hard, glossy and solvent-resistant.

EXAMPLE XVll An amine of the formula was produced from the reaction ofdimethylamine with methyl methacrylate in aqueous solution. Followingthe procedure of the above examples, 27.8 parts of this amine werereacted with 250 parts of polyepoxide (diglycidyl ether of Bisphenol A,epoxide equivalent 185200; Epi-Rez 510") in the presence of 77 parts ofthe dimethyl ether of diethylene glycol. Water and formic acid were usedto reduce the solids content to 5 percent and the pH to 5.9.Electrodeposition of the product on strips of zinc phosphate-treatedsteel at 200 volts for 20 seconds provided adherent films which afterbaking at 385F. for 30 minutes were hard, glossy, extremelysolvent-resistant coatings.

EXAMPLE XVlll Into a reaction vessel equipped with stirrer, thermometer,condenser, inert gas sparge and heating element was charged 336 parts ofEpon 829 and 1 13 parts of Bisphenol A. The mixture was heated to 180C.,at which time an exotherm was noted. The reaction mixture was held atl80-190C. for 45 minutes. The reaction mixture was then cooled to 110C., at which time 40 parts of isopropanol were added. The reactionmixture was further cooled to 80C. and a solution comprising 42.7 partsof 2-(B-dimethylaminoethoxy)-4- methyl-1,3,2-dioxaborinane and 10.7parts of isopropanol were added over a 20 minute period at a temperaturebetween 80 and C. The reaction mixture was held at 94C. for 5 minutesafter the addition. There was then added 107 parts of water over a4-minute period. There resulted a clear brown resin solution.

To the solution at a temperature of 74C. was added a solution of 2.4parts of Foam-Kill 639 dissolved in 33 parts of 2-ethylhexanol. Theresultant resin solution adjusted to percent solids, had the followingcharacteristics:

Epoxy value Hydroxyl value EXAMPLE XIX baked film (350F. for 25 minutes)was rough and contained bubbles. Analysis of the electrodeposition bathyielded the following data:

Milliequivalents of quaternary base groups per millimeter 0.0374Milliequivalents of amine groups per milliliter 0.0038 Milliequivalentsof boric acid per milliliter 0.0444

Part B To 272 parts of the resin solution of Example XVIII were addedparts of 85 percent lactic acid and 1630 parts of deionized water toyield an electrodepositable composition containing 10.3 percent solidsand a pH of 6.3. The resin was easily dispersed and had an almost clearcolloidal appearance. The composition had a rupture voltage of 400 voltsat 80F. and when a zinc phosphated steel plane was electrodeposited,smooth films resulted. When baked at 350F. for 25 minutes, a smooth,solvent-resistant film at 61-1 pencil hardness was obtained Theelectrodeposition bath yielded the following analytical results:

Milliequivalents of quaternary base groups per milliliter 0.0419Milliequivalents of amine groups per milliliter 0.0013 Milliequivalentsof lactic acid per milliliter 0.0437 Milliequivalents of boric acid permilliliter 0.0484

Particle size of the dispersions of Part A and Part B were determined bylight scattering techniques. In a light source of 4358 angstroms, Part Adisplayed a particle size of 560 angstroms and Part B displayed aparticle size of 290 angstroms; with a light source of 5460 angstroms,Part A displayed a particle size of 630 angstroms and Part B displayed aparticle size of 300 angstroms.

EXAMPLE XX Into a reactor as described in Example XVIII was charged 1000parts of Epon 829 and 335 parts of Bisphenol A. The reaction mixture washeated to 170C. at which time an exotherm was noted. The reactionmixture was held at 180l85C. for 45 minutes. The reaction mixture wasthen cooled to 117C. and there was added 125 parts of isopropanol. Thereaction mixture was further cooled to 80C. and there was added Epoxyvalue Hydroxyl value To 272 parts of the above resin solution was added1630 parts of deionized water. The resin was easily dispersed to yield ablue-green colloidal solution containing 9.74 percent solids and a pH of6.8. The electrodepositable composition displayed a rupture voltage of410 volts at F. Zinc phosphated steel panels were electrocoated at 250volts for seconds at a bath temperature of 85F. There resulted anelectrodeposited film which when baked at 350F. for 25 minutes yielded aslightly textured smooth glossy film.

The elctrodeposition bath yielded the following analysis:

Milliequivalents of quarternary base groups per milliliter 0.0379Milliequivalents of amine groups per milliliter 0.0011 Milliequivalentsof lactic acid per milliliter 0.0374 Milliequivalents of boric acid permilliliter 0.0392

EXAMPLE XXI Into a reactor equipped as described in Example XVIII wascharged 500 parts of Epon 840 and 65 parts of isophorone.

A salt solution was prepared by admixing 32.5 parts ofdimethylethyanolamine, 22.5 parts of acetic acid and 15.5 parts ofisopropanol. The salt solution was added to the above resin solutionbeginning at a temperature of 49C. over a period of 20 minutes, with thetemperature ranging from 49C. to 75C. After the addition was completethe reaction mixture was held at 7585C. for an additional 5 minutes.There was then added 287 parts of deionized water over a 5-minute periodto yield the resin solution at a temperture of 62C. The analysis of theresin, adjusted to percent solids, was as follows:

Epoxy value 650 Hydroxyl value Quaternary acetate groups per gram ofresin 0.3644 7 Milliequivalents of amine acetate per gram of resin 0.085

To 215 parts of the above resin solution was added 1200 parts ofdeionized water. The resultant electrodeposition bath had a pH of 8.5.Films when electrodeposited at volts were rough, hard films.

EXAMPLE XXII Into a reactor as described in Example XVIII were charged500 parts of Epon 840 and 65 parts of isophorone. A salt solution wasprepared from 32.2 parts of dimethylethanolamine and 22.8 parts of boricacid and 15.5 parts of isopropanol and 20 parts of deionized water. Thesalt solution was added to the above resin solution beginning at atemperature of 55C. over a 20- minute period with the temperatureranging from 55-76C. The reaction mixture was held for five minutes at atemperature of 76-85C after the addition was complete. There was thenadded 287 parts of deionized water over a 4-minute period to yield aresin solution at 62C. The analysis of the resin solution. adjusted to100 percent solids, was as follows:

Epoxy value Hydroxyl value Milliequivalents of quarternary base groupsper milliliter 0.0602 Milliequivalents of boric acid per milliliter0.0657

Milliequivalents of quarternary base per milliliter 0.0617Milliequivalents of lactic acid 0.0337 Milliequivalents of boric acidper milliliter 0.0693

The wet electrodepositable film was analyzed to contain 0.1474milliequivalents of quarternary borate groups per gram. The wet film hada solids content of 66.9 percent.

EXAMPLE XXIII Into a reactor as described in Example XVII were charged400 parts of Epon 829 and 100 parts of Bisphenol A. The reaction mixturewas heated to 170C. at which time an exotherm occurred. The reactionmixture was heated at 175l84C. for 45 minutes and then cooled to 155C.There was then added 90 parts of isophorone, and the reaction mixturewas cooled to 70C. The reaction mixture is hereinafter referred to asthe base resin.

There was then added a solution of 55 parts of Example A and 14 parts ofisopropanol over a 20 minute period at temperatures between 7090C. Afterthe addition was complete, the reaction mixture was held at 90-96C. foran additional minutes. There was then added 295 parts of deionized waterover a minute period. There resulted a resin solution which wasapparently clear while being stirred and appeared pearlescent while atrest. The resin solution was analyzed to contain, adjusted to 100percent solids:

Epoxy value Hydroxyl value for 90 seconds at 77F. and baked at 350-380F.for 30 minutes yielded films of 0.4 mil with a pencil hardness of 6H.The films were smooth and glossy. The electrodeposition bath analyzed tocontain:

Milliequivalents of quaternary base groups 10 per milliliter 0.0293Milliequivalents of lactic acid per milliliter 0.0280 1 Milliequivalentsof boric acid per milliliter 0.03l l To the base resin as describedabove was added 55 parts of Z-(B-dimethylaminoethoxy)-4-methyl-1,3,2-dioxaborinane at a temperature of -89C. over a 20 minute period. Thereaction mixture was held for 5 minutes at 89100C. after the additionwas complete. There was then added 285 parts deionized water over a 4minute period and a clear resinous solution was obtained having an epoxyvalue adjusted to 100 percent solids of 582 and a hydroxyl value (100percent solids) of 132.5.

To 215 parts of this resin solution was added 1285 parts of deionizedwater to yield an electrodeposition bath having a pH of 8.9. Theelectrodeposition bath displayed a throw power of 2% inch.Zinc-phosphated steel panels were electrodeposited at 200 volts in 90seconds at 77F. and baked and the resultant film build was 0.25 to 0.3mil with a 6H+ pencil hardness.

The electrodepositable composition analyzed to contam:

Milliequivalents of quaternary base groups per milliliter 0.0420Milliequivalents of boric acid per milliliter 0.05 l0 EXAMPLE XXI\ Intoa reactor as described in Example XVIII was charged 500 parts of Epon834. The resin was heated to 80C. A salt solution comprising 1 12.3parts of 40% dimethylamine in water, and 106 parts of lactic acid inwater, having a pH of 4.3, was added at a temperature of 80-85C. over a20 minute period. The reaction mixture was then heated to 97C. andrefluxed for 20 minutes. There was then added 169 parts of deionizedwater, followed by 100 parts of ethyl Cellosolve and 10 parts of percentformic acid. The resin dispersion was somewhat cloudy. There was thenadded to the resin dispersion sufficient water to form a 10 percentsolids bath. Sufficient formic acid was added to adjust the pH to 2.5.

An aluminum strip was electrocoated at a bath temperature of 80F. atvolts for 60 seconds. The film was deposited on the cathode, which wasbaked at 350F. for 20 minutes. A glossy, hard yellow film was obtained.

The resin at 100 percent solids had the following properties:

Epoxy value Hydroxyl value Milliequivalents of amine per gram EXAMPLEXXV Into a reactor as described in Example XVIII was charged 500 partsof Epon 834. This resin was heated to 80C. and there was added a saltsolution formed by admixing 101 parts of dipropylamine and 106 parts 85percent lactic acid, together with 33 parts of isopropanol. The saltsolution was added at 80-85C. with heat over a 20 minute period. Afterthe addition was complete, the reaction mixture was heated to 95C. andrefluxed for 20 minutes. 167 parts of deionized water were then added. Acloudy resin dispersion was obtained, to which was added 100 parts ethylCellosolve, parts of 90 percent formic acid. A clear yellow resinsolution was obtained.

Analysis of the product adjusted to 100 percent solids is as follows:

Epoxy value Hydroxyl value The resin was analyzed to contain:

Milliequivalents of amine per gram Useful electrodeposited films wereobtained.

EXAMPLE XXVI Into a reactor equipped with stirrer, thermometercondenser, inert gas inlet and heating element was charged 1,005 partsof Epon 829 and 339 parts of bisphenol-A. The mixture was heated to180C. and held for 45 minutes at 180-I88C.'There was then added at 120C.114 parts of isopropanol and the mixture cooled to 79C. There was thenadded 141.0 parts of a 75 percent solids solution in isopropanol ofdimethylethanolamine lactate over a minute period between 79C. and 93C.with heating. The reaction mixture was held at 93C97C. for twoadditional minutes, and there was then added 425 parts of deionizedwater over a four minute period at which time the temperature was 75C.

There was then added a solution of 7 parts of Foam Kill 639 in 90 partsof 2-ethylhexanol. A clear yellow resin solution was obtained. This ishereinafter referred to as the base resin.

Analysis I007! solids) Epoxy value 1085 Hydroxyl value 233 at F. Uniformfilm build was noted. The film was baked at 350F. for 30 minutes toyield a glossy film, 0.45 mils, pencil hardness 6H; Film electrocoatedat 300 volts for seconds at 80F. and baked as above yielded 0.5 milspencil hardness 6H.

To the same bath was added 6.6 parts of boric acid. The bath had a ph of6.4. Film electrocoated and baked as above yielded:

250 volts 300 volts Other reaction products can be formed and utilizedin the foregoing invention using other epoxy compounds, amine, acids,salts and boron compounds as described above. Similarly, otherconditions and adjuvants and the like may be employed to formulate andutilize the coating compositions as desired.

According to the provision of the Patent Statutes, there are describedabove the invention and what are now considered to be its bestembodiments. However, within the scope of the appended claims. it is tobe understood that the invention can be practiced otherwise than asspecifically described.

We claim:

1. An aqueous dispersion comprising a. an ungelled water-dispersed epoxyresin, having in the resin molecule at least one 1,2 epoxy group, atleast about 0.05 percent by weight of chemicallybound nitrogen in theform of a quaternary ammonium base salt of an acid having a dissociationconstant greater than 1 X 10 and b. boric acid said dispersioncontaining sufficient boron to catalyze the cure of a film of said epoxyresin.

2. An aqueous dispersion as in claim 1 whrein at least about 20 percentof the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

3. An aqueous dispersion as in claim 2 wherein at least about 50 percentof the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

4. A resin as in claim 2 wherein substantially all of the nitrogen insaid epoxy resin is in the form of quaternary ammonium base salt groups.

5. An aqueous dispersion as in claim 1 wherein the acid is an organiccarboxylic acid.

6. An aqueous dispersion as in claim 5 wherein at least about 20 percentof the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

7. An aqueous dispersion as in claim 6 wherein at least about 50 percentof the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

8. An aqueous dispersion as in claim 7 wherein substantially all of thenitrogen in said epoxy resin is in the form of quaternary ammonium basesalt groups.

9. An aqueous dispersion as in claim 1 wherein the acid is lactic acid.

10. An aqueous dispersion as in claim 1 wherein the acid salt is in theform of an internal zwitterion.

11. An aqueous dispersion as in claim 9 wherein at least about 20percent of the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

12. An aqueous dispersion as in claim-9 wherein at least about 50percent of the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.

13. An aqueous dispersion as in claim 9 wherein substantially all of thenitrogen in said epoxy resin is in the form of quaternary ammonium basesalt groups.

14. An aqueous dispersion as in claim 1 wherein said epoxy resin isderived from a polyglycidyl ether of a polyphenol.

15. An aqueous dispersion as in claim '1 wherein said epoxy resin isderived from a polyglycidyl ether of bis(- 4-hydroxyphenyl)-2,2-propane.

16. An aqueous dispersion as in claim 1 wherein said epoxy resincontains about .05 to about 16 percent by weight of nitrogen.

17. An aqueous dispersion as in claim 1 wherein said aqueous dispersioncontains sufficient boron to provide from 0.01 to about 8 percent boronin a film of said epoxy resin.

18. An aqueous dispersion as in claim 1 wherein said epoxy resincontains oxyalkyene groups.

19. An aqueous dispersion as in claim 1 wherein said quaternary ammoniumbase salt is derived from a tertiary amine salt of an organic acid.

20. An aqueous dispersion as in claim 19 wherein said quaternaryammonium base salt is derived from salt of a hydroxyl amine.

21. An aqueous dispersion as in claim 1 wherein said quaternary ammoniumbase salt is derived from dimethylethanol amine lactate.

22. An aqueous electrodeposition bath which comprises an aqueousdispersion comprising:

' b. boric acid said dispersion containing sufficient boron to catalyzethe cure of a film of said epoxy resin.

23. An aqueous electrodeposition bath as in claim 22 which contains anorganic coupling solvent.

24. An aqueous electrodeposition bath as in claim 23 wherein thecoupling solvent comprises 2- ethylhexanol.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.. 3-839 2 52; I Dated October 1, 1974 Inventofl) Joseph F. Bos so and MarcoWismer It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

The recitation of the inventors and their addresses shouldi'ead:

-- Joseph/1?- B0580, ever fiurrlll ends-Mer .W r' Gibsonia, both-,,o.Pa. V

Signed and sealed this 17th day of December 1974'.

(SEAL) Attest:

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM Po-wso (10-69)

1. AN AQUEOUS DISPERSION COMPRISING . AN UNGELLED WATER-DISPERSED EPOXYRESIN, HAVING IN THE RESIN MOLECULE AT LEAST ONE 1,2 EPOXY GROUP, ATLEAST ABOUT 0.05 PERCENT BY WEIGHT OF CHEMICALLY-BOUND NITROGEN IN THEFORM OF A QUATERNARY AMMONIUM BASE SALT OF AN ACID HAVING A DISSOCIATIONCONSTANT GREATER THAN 1 X 10-5, AND B. BORIC ACID SAID DISPERSIONCONTAINING SUFFICIENT BORON TO CATALYZE THE CURE OF A FILM OF SAID EPOXYRESIN.
 2. An aqueous dispersion as in claim 1 whrein at least about 20percent of the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.
 3. An aqueous dispersion as in claim 2wherein at least about 50 percent of the nitrogen in said epoxy resin isin the form of quaternary ammonium base salt groups.
 4. A resin as inclaim 2 wherein substantially all of the nitrogen in said epoxy resin isin the form of quaternary ammonium base salt groups.
 5. An aqueousdispersion as in claim 1 wherein the acid is an organic carboxylic acid.6. An aqueous dispersion as in claim 5 wherein at least about 20 percentof the nitrogen in said epoxy resin is in the form of quaternaryammonium base salt groups.
 7. An aqueous dispersion as in claim 6wherein at least about 50 percent of the nitrogen in said epoxy resin isin the form of quaternary ammonium base salt groups.
 8. An aqueousdispersion as in claim 7 wherein substantially all of the nitrogen insaid epoxy resin is in the form of quaternary ammonium base salt groups.9. An aqueous dispersion as in claim 1 wherein the acid is lactic acid.10. An aqueous dispersion as in claim 1 wherein the acid salt is in theform of an internal zwitterion.
 11. An aqueous dispersion as in claim 9wherein at least about 20 percent of the nitrogen in said epoxy resin isin the form of quaternary ammonium base salt groups.
 12. An aqueousdispersion as in claim 9 wherein at least about 50 percent of thenitrogen in said epoxy resin is in the form of quaternary ammonium basesalt groups.
 13. An aqueous dispersion as in claim 9 whereinsubstantially all of the nitrogen in said epoxy resin is in the form ofquaternary ammonium base salt groups.
 14. An aqueous dispersion as inclaim 1 wherein said epoxy resin is derived from a polyglycidyl ether ofa polyphenol.
 15. An aqueous dispersion as in claim 1 wherein said epoxyresin is derived from a polyglycidyl ether ofbis(4-hydroxyphenyl)-2,2-propane.
 16. An aqueous dispersion as in claim1 wherein said epoxy resin contains about .05 to about 16 percent byweight of nitrogen.
 17. An aqueous dispersion as in claim 1 wherein saidaquEous dispersion contains sufficient boron to provide from 0.01 toabout 8 percent boron in a film of said epoxy resin.
 18. An aqueousdispersion as in claim 1 wherein said epoxy resin contains oxyalkyenegroups.
 19. An aqueous dispersion as in claim 1 wherein said quaternaryammonium base salt is derived from a tertiary amine salt of an organicacid.
 20. An aqueous dispersion as in claim 19 wherein said quaternaryammonium base salt is derived from salt of a hydroxyl amine.
 21. Anaqueous dispersion as in claim 1 wherein said quaternary ammonium basesalt is derived from dimethylethanol amine lactate.
 22. An aqueouselectrodeposition bath which comprises an aqueous dispersion comprising:a. an ungelled water-dispersed epoxy resin having in the resin moleculeat least one 1,2 epoxy group, at least about 0.05 percent by weight ofchemically-bound nitrogen in the form of a quaternary ammonium base saltgroup of an acid having a dissociation constant greater than 1 X 10 5,said quaternary ammonium base salt group having been derived from atertiary amine salt of an organic acid, and b. boric acid saiddispersion containing sufficient boron to catalyze the cure of a film ofsaid epoxy resin.
 23. An aqueous electrodeposition bath as in claim 22which contains an organic coupling solvent.
 24. An aqueouselectrodeposition bath as in claim 23 wherein the coupling solventcomprises 2-ethylhexanol.